Optical device control apparatus and optical device control method

ABSTRACT

The inclination of a reflecting surface of a mirror is adjusted such that light outputted from an input optical fiber is reflected by the mirror so as to be fed into an output optical fiber. The normal direction of the reflecting surface of the mirror vibrates about a predetermined direction at a predetermined frequency. A part of the light propagating through the output optical fiber is taken out by a light-branching part, so as to be received by a photodiode, whereby an electric signal having a value corresponding to thus received quantity of light is outputted from a detection circuit. Whether or not the electric signal includes a component of the predetermined frequency or whether the component is strong or weak is detected, whereby whether or not there is optical coupling from the input optical fiber to the output optical fiber or the extent thereof is determined.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Provisional Application Ser. No.60/486,173 filed on Jul. 11, 2003 which are hereby incorporated byreference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus and a method forcontrolling optical device in which light emitted from an input opticalwaveguide is reflected by an inclinable reflecting surface so as to bemade incident on an output optical waveguide.

2. Related Background of the Invention

Known as an example of optical device including a mirror having aninclinable reflecting surface is one disclosed in Patent Document 1(U.S. Patent Application Laid-Open No. 2002/0076136). This opticaldevice is an optical switch including a plurality of input ports and aplurality of output ports, and can optically couple any input portselected from the plurality of input ports to any output port selectedfrom the plurality of output ports. Here, the input and output ports tobe optically coupled to each other are selected by adjusting theinclination of the reflecting surface of the mirror. Such a mirrorhaving an inclinable reflecting surface is made by MEMS(microelectromechanical systems) technology, for example. In such a MEMSmirror, the inclination of the reflecting surface is set according tothe applied voltage value.

In order for such an optical device to carry out its operations at ahigh accuracy, it is important that the inclination of the reflectingsurface of the mirror be controlled with a high accuracy. Therefore, inthe optical device disclosed in the above-mentioned Patent Document 1,an optical multiplexer and an optical demultiplexer are disposed in anoptical path from the plurality of input ports to the plurality ofoutput ports. The optical multiplexer inserts pilot light into theoptical path. The pilot light is reflected by the mirror, and is takenout from the optical demultiplexer. Thus taken pilot light is detectedby a sensor, so that the state of inclination of the reflecting surfaceof the mirror is detected, whereby its inclination is controlled.

SUMMARY OF THE INVENTION

However, though the above-mentioned optical device can detect andcontrol the inclination of the reflecting surface of the mirror, it canneither detect nor control with a high accuracy whether or not there isoptical coupling from an input port to an output port or an extentthereof.

For eliminating the problem mentioned above, it is an object of thepresent invention to provide an optical device control apparatus and anoptical device control method which can detect and control with a highaccuracy whether or not there is optical coupling or an extent thereofin the optical device.

The optical device control apparatus or method in accordance with thepresent invention is an apparatus or method for controlling an opticaldevice including a mirror in which light emitted from an input opticalwaveguide is reflected by an inclinable reflecting surface so as to bemade incident on an output optical waveguide, and a mirror driving partfor adjusting an inclination of the reflecting surface of the mirror. Anoptical module in accordance with the present invention comprises suchan optical device and the optical device control apparatus in accordancewith the present invention for controlling the optical device.

The optical device control apparatus comprises (1) a light-branchingpart for taking out a part of the light propagating through the outputoptical waveguide after being made incident thereon; (2) alight-detecting part for detecting an intensity of the light taken outby the light-branching part and outputting an electric signal having avalue corresponding to thus detected intensity of light; and (3) acontrol part for ordering the mirror driving part to vibrate a normaldirection of the reflecting surface of the mirror at a predeterminedfrequency about a predetermined direction, detecting a component of thepredetermined frequency in the electric signal outputted from thelight-detecting part, and determining whether or not there is opticalcoupling from the input optical waveguide to the output opticalwaveguide or an extent thereof according to a result of the detection.

The optical device control method in accordance with the presentinvention comprises the steps of taking out a part of the lightpropagating through the output optical waveguide after being madeincident on the output optical waveguide; obtaining an electric signalhaving a value corresponding to an intensity of the part of the light;and ordering the mirror driving part to vibrate a normal direction ofthe reflecting surface of the mirror at a predetermined frequency abouta predetermined direction, detecting a component of the predeterminedfrequency in the electric signal, and determining whether or not thereis optical coupling from the input optical waveguide to the outputoptical waveguide or an extent thereof according to a result of thedetection.

According to the present invention, the intensity of light propagatingthrough the output optical waveguide after being made incident thereonis detected, whereby an electric signal having a value corresponding tothe intensity of light is obtained. The normal direction of thereflecting surface of the mirror is driven by the mirror driving part,so as to vibrate at a predetermined frequency about a predetermineddirection, and a component of the predetermined frequency in theelectric signal is detected. According to the result of detection,whether or not there is optical coupling from the input opticalwaveguide to the output waveguide or an extent thereof is directlydetermined. Examples of the optical device include optical switches,variable optical attenuators, and wavelength-selecting switches.

Preferably, the control part of the optical device control apparatus inaccordance with the present invention controls the extent of opticalcoupling from the input optical waveguide to the output opticalwaveguide by ordering the mirror driving part to adjust the normaldirection of the reflecting surface of the mirror according to theresult of detection. Preferably, the optical device control method inaccordance with the present invention controls the extent of opticalcoupling from the input optical waveguide to the output opticalwaveguide by ordering the mirror driving part to adjust the normaldirection of the reflecting surface of the mirror according to theresult of detection. When the optical device is an optical switch, forexample, the extent of optical coupling from the input optical waveguideto the output optical waveguide is controlled so as to become themaximum value or a value not smaller than a certain threshold. When theoptical device is a variable optical attenuator, the extent of opticalcoupling from the input optical waveguide to the output opticalwaveguide is controlled so as to become a certain set value.

When the optical device comprises a plurality of mirrors, it ispreferred that the control part of the optical device control apparatusin accordance with the present invention orders the mirror driving partto vibrate respective normal directions of reflecting surfaces of themirrors at frequencies different from each other. Preferably, in thiscase, the optical device control method in accordance with the presentinvention orders the mirror driving part to vibrate respective normaldirections of reflecting surfaces of the mirrors at frequenciesdifferent from each other. This makes it possible to determine by whichmirror the light coupled to an output optical fiber is reflected.

When the optical device comprises a plurality of input opticalwaveguides, it is preferred that the control part of the optical devicecontrol apparatus in accordance with the present invention orders themirror driving part to vibrate the normal direction of the reflectingsurface of the mirror at respective frequencies different from eachother for the input optical waveguides. Preferably, in this case, theoptical device control method in accordance with the present inventionorders the mirror driving part to vibrate the normal direction of thereflecting surface of the mirror at respective frequencies differentfrom each other for the input optical waveguides. This makes it possibleto determine from which input optical fiber the light coupled to anoutput optical fiber is inputted.

When the optical device further comprises an opticalmulti/demultiplexing part for multiplexing or demultiplexing light ontoan optical path from the input optical waveguide to the output opticalwaveguide, it is preferred that the control part of the optical devicecontrol apparatus in accordance with the present invention orders themirror driving part to vibrate the normal direction of the reflectingsurface of the mirror at respective frequencies different from eachother for wavelengths of light multiplexed or demultiplexed by theoptical multi/demultiplexing part. Preferably, in this case, the opticaldevice control method in accordance with the present invention ordersthe mirror driving part to vibrate the normal direction of thereflecting surface of the mirror at respective frequencies differentfrom each other for wavelengths of light multiplexed or demultiplexed bythe optical multi/demultiplexing part. This makes it possible todetermine at which wavelength the light is coupled to an output opticalfiber.

When the optical device comprises a plurality of input opticalwaveguides and further comprises an optical multi/demultiplexing partfor multiplexing or demultiplexing light onto an optical path from theinput optical waveguide to the output optical waveguide, while thereflecting surface of the mirror is inclinable about each of two axes,it is preferred that the control part orders the mirror driving part tovibrate the normal direction of the reflecting surface of the mirror ona first surface at respective frequencies different from each other forthe plurality of input optical waveguides, and vibrate the normaldirection of the reflecting surface of the mirror on a second surface atrespective frequencies different from each other for wavelengths oflight multiplexed or demultiplexed by the optical multi/demultiplexingpart. Preferably, in this case, the optical device control method inaccordance with the present invention orders the mirror driving part tovibrate the normal direction of the reflecting surface of the mirror ona first surface at respective frequencies different from each other forthe plurality of input optical waveguides, and vibrate the normaldirection of the reflecting surface of the mirror on a second surface atrespective frequencies different from each other for wavelengths oflight multiplexed or demultiplexed by the optical multi/demultiplexingpart. This makes it possible to determine from which input optical fiberand at which wavelength the light is coupled to an output optical fiber.

The control part of the optical device control apparatus in accordancewith the present invention may order the mirror driving part to vibratethe reflecting surface of the mirror and detect the component of thepredetermined frequency in the electric signal outputted from thelight-detecting part for a plurality of mirrors either regularly or inresponse to a request from outside. The optical device control method inaccordance with the present invention may order the mirror driving partto vibrate the reflecting surface of the mirror and detect the componentof the predetermined frequency in the electric signal either regularlyor in response to a request from outside. For regularly carrying outthese operations, it will be sufficient if the mirror is alwaysvibrated, which can simplify the configuration of the mirror drivingpart. Carrying out the operations in response to a request from outsidecan prevent vibrations at the same frequency from interfering with eachother, for example, when a plurality of optical devices are connected toeach other.

When the optical device comprises a plurality of mirrors, the controlpart of the optical device control apparatus in accordance with thepresent invention may order the mirror driving part to vibrate thereflecting surface of the mirror and detect the component of thepredetermined frequency in the electric signal outputted from thelight-detecting part either sequentially or simultaneously for theplurality of mirrors. In this case, the optical device control method inaccordance with the present invention may order the mirror driving partto vibrate the reflecting surface of the mirror and detect the componentof the predetermined frequency in the electric signal eithersequentially or simultaneously for the plurality of mirrors. When aplurality of mirrors are sequentially processed, the number of A/D andD/A conversions is reduced, whereby the configuration of the mirrordriving part can be made simpler. When a plurality of mirrors aresimultaneously processed, on the other hand, the mirrors can becontrolled at a high speed.

Though the present invention is one in which the extent of opticalcoupling to the output optical waveguide is changed by vibrating amirror, it is not restrictive. The extent of optical coupling to theoutput optical waveguide may be changed by an action of any otherconstituent (e.g., electrooptic effect, magnetooptic effect, orpolarized wave control by a liquid crystal) included in the opticaldevice.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram which shows a configuration of an optical module 1in accordance with the first embodiment;

FIG. 2 is a diagram which shows a configuration of an optical module 2in accordance with the second embodiment; and

FIG. 3 is a diagram which shows a configuration of an optical module 3in accordance with the third embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the following, best modes for carrying out the present invention willbe explained in detail with reference to the accompanying drawings. Inthe explanation of the drawings, constituents identical to each otherwill be referred to with symbols identical to each other withoutrepeating their overlapping descriptions.

[First Embodiment]

A first embodiment of an optical device control apparatus and method andoptical module in accordance with the present invention will initiallybe explained. FIG. 1 is a diagram which shows a configuration of theoptical module 1 in accordance with the first embodiment. The opticalmodule 1 shown in this drawing comprises an optical device 1A and anoptical device control apparatus 1B. The optical device 1A includesinput optical fibers 11 ₁, 11 ₂; output optical fibers 12 ₁, 12 ₂;mirrors 13 ₁, 13 ₂; and mirror driving parts 14 ₁, 14 ₂. In the opticaldevice 1A, light components emitted from respective end faces of theinput optical fibers 11 ₁, 11 ₂ are made incident on any of end faces ofthe output optical fibers 12 ₁, 12 ₂. The optical device controlapparatus 1B includes light-branching parts 15 ₁, 15 ₂; photodiodes 16₁, 16 ₂; detection circuits 17 ₁, 17 ₂; and a control part 19; andcontrols the optical device 1A.

Each of the mirrors 13 ₁, 13 ₂ has an inclinable reflecting surface. Themirror 13 ₁ reflects the light emitted from the end face of the inputoptical fiber 11 ₁ with the reflecting surface, and makes thus reflectedlight incident on the end face of any of the output optical fibers 12 ₁,12 ₂. On the other hand, the mirror 13 ₂ reflects the light emitted fromthe end face of the input optical fiber 11 ₂ with the reflectingsurface, and makes thus reflected light incident on the end face of anyof the output optical fibers 12 ₁, 12 ₂.

According to an instruction from the control part 19, the mirror drivingpart 14 ₁ drives the mirror 13 ₁, so as to adjust the inclination of thereflecting surface of the mirror 13 ₁. On the other hand, according toan instruction from the control part 19, the mirror driving part 14 ₂drives the mirror 13 ₂, so as to adjust the inclination of thereflecting surface of the mirror 13 ₂.

For achieving a small size, it will be preferred if each of the mirrors13 ₁, 13 ₂ is made by MEMS technology. In this case, the mirror drivingparts 14 ₁, 14 ₂ can adjust the inclinations of the reflecting surfacesof the mirrors 13 ₁, 13 ₂ by adjusting voltage values applied to themirrors 13 ₁, 13 ₂.

The light-branching part 15 ₁ is disposed in the output optical fiber 12₁, and takes out a part of light propagating through the output opticalfiber 12 ₁ after being made incident on the end face of the outputoptical fiber 12 ₁. On the other hand, the light-branching part 15 ₂ isdisposed in the output optical fiber 12 ₂, and takes out a part of lightpropagating through the output optical fiber 12 ₂ after being madeincident on the end face of the output optical fiber 12 ₂.

The photodiode 16 ₁ receives the light component taken out by thelight-branching light 15 ₁ from the light propagating through the outputoptical fiber 12 ₁, and outputs a current signal having a valuecorresponding to the intensity of thus received light. The detectioncircuit 17 ₁ inputs the current signal outputted from the photodiode 16₁, converts the current signal into a voltage signal, and outputs thisvoltage signal. The photodiode 16 ₁ and detection circuit 17 ₁ act as alight-detecting part for outputting an electric signal having a valuecorresponding to the intensity of light taken out by the light-branchingpart 15 ₁.

The photodiode 16 ₂ receives the light component taken out by thelight-branching light 15 ₂ from the light propagating through the outputoptical fiber 12 ₂, and outputs a current signal having a valuecorresponding to the intensity of thus received light. The detectioncircuit 17 ₂ inputs the current signal outputted from the photodiode 16₂, converts the current signal into a voltage signal, and outputs thisvoltage signal. The photodiode 16 ₂ and detection circuit 17 ₂ act as alight-detecting part for outputting an electric signal having a valuecorresponding to the intensity of light taken out by the light-branchingpart 15 ₂.

The control part 19 causes the mirror driving parts 14 ₁, 14 ₂ tocontrol the respective inclinations of the reflecting surfaces of themirrors 13 ₁, 13 ₂, thereby making the optical module 1 act as anoptical switch. Namely, the control part 19 can cause the lightoutputted from the end face of the input optical fiber 11 ₁ to be madeincident on the end face of the output optical fiber 12 ₁, and the lightoutputted from the end face of the input optical fiber 11 ₂ to be madeincident on the end face of the output optical fiber 12 ₂. The controlpart 19 can cause the light outputted from the end face of the inputoptical fiber 11 ₁ to be made incident on the end face of the outputoptical fiber 12 ₂, and the light outputted from the end face of theinput optical fiber 11 ₂ to be made incident on the end face of theoutput optical fiber 12 ₁. The control part 19 can cause both of thelight components outputted from the respective end faces of the inputoptical fibers 11 ₁ and 11 ₂ to be made incident on the end face of theoutput optical fiber 12 ₁. The control part 19 can cause both of thelight components outputted from the respective end faces of the inputoptical fibers 11 ₁ and 11 ₂ to be made incident on the end face of theoutput optical fiber 12 ₂.

In FIG. 1, the control part 19 causes the mirror 13 ₁ to reflect thelight outputted from the end face of the input optical fiber 11 ₁, so asto make the light incident on the end face of the output optical fiber12 ₂, and also causes the mirror 13 ₂ to reflect the light outputtedfrom the end face of the input optical fiber 11 ₂, so as to make thelight incident on the end face of the output optical fiber 12 ₁.

The control part 19 orders the mirror driving part 14 ₁ to vibrate thenormal direction of the reflecting surface of the mirror 13 ₁ at afrequency f₁ about a predetermined direction, detects a component of thefrequency f₁ in the electric signal outputted from the detection circuit17 ₂, and determines whether or not there is optical coupling from theinput optical fiber 11 ₁ to the output optical fiber 12 ₂ or the extentthereof according to the result of detection. Further, according to theresult of detection, the control part 19 orders the mirror driving part14 ₁ to adjust the normal direction of the reflecting surface of themirror 13 ₁, thereby controlling the extent of optical coupling from theinput optical fiber 11 ₁ to the output optical fiber 12 ₂.

The control part 19 orders the mirror driving part 14 ₂ to vibrate thenormal direction of the reflecting surface of the mirror 13 ₂ at afrequency f₂ about a predetermined direction, detects a component of thefrequency f₂ in the electric signal outputted from the detection circuit17 ₁, and determines whether or not there is optical coupling from theinput optical fiber 11 ₂ to the output optical fiber 12 ₁ or the extentthereof according to the result of detection. Further, according to theresult of detection, the control part 19 orders the mirror driving part14 ₂ to adjust the normal direction of the reflecting surface of themirror 13 ₂, thereby controlling the extent of optical coupling from theinput optical fiber 11 ₂ to the output optical fiber 12 ₁.

An example of operation of the optical module 1 in accordance with thefirst embodiment will now be explained together with the optical devicecontrol method in accordance with the first embodiment. Under thecontrol of the control part 19, the optical module 1 operates asfollows, for example. The light outputted from the end face of the inputoptical fiber 11 ₁ is made incident on the reflecting surface of themirror 13 ₁, whereas the light outputted from the end face of the inputoptical fiber 11 ₂ is made incident on the reflecting surface of themirror 13 ₂.

In response to an order to switch between optical paths from the controlpart 19, the mirror driving part 14 ₁ adjusts the inclination of thereflecting surface of the mirror 13 ₁ such that the light outputted fromthe end face of the input optical fiber 11 ₁ is reflected by the mirror13 ₁ so as to be fed to the end face of the output optical fiber 12 ₂.Taking the normal direction of the reflecting surface of the mirror 13 ₁after the adjustment as a predetermined direction, the normal directionof the reflecting surface of the mirror 13 ₁ is driven by the mirrordriving part 14 ₁, so as to vibrate at the frequency f₁ about thepredetermined direction. The light reflected by the reflecting surfaceof the mirror 13 ₁ is fed to the end face of the output optical fiber 12₂ and propagates through the output optical fiber 12 ₂. A part of theguided light is caused to branch out and taken out by thelight-branching part 15 ₂, so as to be received by the photodiode 16 ₂,whereby the detection circuit 17 ₂ outputs an electric signal having avalue corresponding to the quantity of light received.

As the reflecting surface of the mirror 13 ₁ vibrates at the frequencyf₁, the intensity of the light propagating through the output opticalfiber 12 ₂ is intensity-modified at the frequency f₁ with time, wherebythe electric signal outputted from the detection circuit 17 ₂ is alsointensity-modified at the frequency f₁ with time. The control part 19detects whether or not the electric signal includes a component of thefrequency f₁ or whether the component is strong or weak. According tothe result of detection, whether or not there is optical coupling fromthe input optical fiber 11 ₁ to the output optical fiber 12 ₂ or theextent thereof is determined. Further, according to the result ofdetection, the mirror driving part 14 ₁ adjusts the normal direction ofthe reflecting surface of the mirror 13 ₁ (the predetermined directionto become the center of vibration), whereby the extent of opticalcoupling from the input optical fiber 11 ₁ to the output optical fiber12 ₂ is regulated so as to become a predetermined value (e.g., a maximumvalue, a value not smaller than a certain threshold, or a certain setvalue).

Similarly, in response to an order to switch between optical paths fromthe control part 19, the mirror driving part 14 ₂ adjusts theinclination of the reflecting surface of the mirror 13 ₂ such that thelight outputted from the end face of the input optical fiber 11 ₂ isreflected by the mirror 13 ₂ so as to be fed to the end face of theoutput optical fiber 12 ₁. Taking the normal direction of the reflectingsurface of the mirror 13 ₂ after the adjustment as a predetermineddirection, the normal direction of the reflecting surface of the mirror13 ₂ is driven by the mirror driving part 14 ₂, so as to vibrate at thefrequency f₂ about the predetermined direction. The light reflected bythe reflecting surf ace of the mirror 13 ₂ is fed to the end face of theoutput optical fiber 12 ₁ and propagates through the output opticalfiber 12 ₁. A part of the guided light is caused to branch out and takenout by the light-branching part 15 ₁, so as to be received by thephotodiode 16 ₁, whereby the detection circuit 17 ₁ outputs an electricsignal having a value corresponding to the quantity of light received.

As the reflecting surface of the mirror 13 ₂ vibrates at the frequencyf₂, the intensity of the light propagating through the output opticalfiber 12 ₁ is intensity-modified at the frequency f₂ with time, wherebythe electric signal outputted from the detection circuit 17 ₁ is alsointensity-modified at the frequency f₂ with time. The control part 19detects whether or not the electric signal includes a component of thefrequency f₂ or whether the component is strong or weak. According tothe result of detection, whether or not there is optical coupling fromthe input optical fiber 11 ₂ to the output optical fiber 12 ₁ or theextent thereof is determined. Further, according to the result ofdetection, the mirror driving part 14 ₂ adjusts the normal direction ofthe reflecting surface of the mirror 13 ₂ (the predetermined directionto become the center of vibration), whereby the extent of opticalcoupling from the input optical fiber 11 ₂ to the output optical fiber12 ₁ is regulated so as to become a predetermined value.

As such, the optical module 1 in accordance with this embodimentdirectly determines whether or not there is optical coupling from theinput optical fiber to the output optical fiber or the extent thereof,and thus can detect and control the extent of optical coupling with ahigh accuracy. Vibrating the normal direction of the reflecting surfaceof one mirror 13 ₁ at the frequency f₁ and the normal direction of thereflecting surface of the other mirror 13 ₂ at the frequency f₂ (≠f₁)can determine which of the mirrors 13 ₁, 13 ₂ reflects the light coupledto the output optical fiber 12 ₁, 12 ₂. Vibrating the normal directionof the reflecting surface of the mirror reflecting the light emittedfrom the end face of one input optical fiber 11 ₁ at the frequency f₁and the normal direction of the reflecting surface of the mirrorreflecting the light emitted from the end face of the other inputoptical fiber 11 ₂ at the frequency f₂ (≠f₁) can determine from which ofthe input optical fibers 11 ₁, 11 ₂ the light coupled to the opticalfiber 12 ₁, 12 ₂ is inputted.

The controller 19 may order the mirror driving parts 14 ₁, 14 ₂ tovibrate the reflecting surfaces of the mirrors 13 ₁, 13 ₂ and detectcomponents of frequencies f₁, f₂ from the electric signals outputtedfrom the detection circuits 17 ₁, 17 ₂ either regularly or in responseto a request from outside (e.g., immediately after switching betweenpaths from an input optical fiber to an output optical fiber). Forregularly carrying out these operations, it will be sufficient if themirrors 13 ₁, 13 ₂ are always vibrated, which can simplify theconfiguration of the mirror driving parts 14 ₁, 14 ₂. Carrying out theoperations in response to a request from outside can prevent vibrationsat the same frequency from interfering with each other, for example,when a plurality of optical devices are connected to each other.

The control part 19 may order the mirror driving parts 14 ₁, 14 ₂ tovibrate the reflecting surfaces of the mirrors 13 ₁, 13 ₂ and detect thecomponents of frequencies f₁, f₂ in the electric signals outputted fromthe detection circuits 17 ₁, 17 ₂ either sequentially or simultaneouslyfor the two mirrors 13 ₁, 13 ₂. When a plurality of mirrors aresequentially processed, the number of A/D and D/A conversions isreduced, whereby the configuration of the mirror driving parts 14 ₁, 14₂ can be made simpler. When a plurality of mirrors 13 ₁, 13 ₂ aresimultaneously processed, on the other hand, the mirrors 13 ₁, 13 ₂ canbe controlled at a high speed.

[Second Embodiment]

A second embodiment of the optical device control apparatus and methodand optical module in accordance with the present invention will now beexplained. FIG. 2 is a diagram which shows a configuration of theoptical module 2 in accordance with the second embodiment. The opticalmodule 2 shown in this drawing comprises an optical device 2A and anoptical device control apparatus 2B. The optical device 2A includes aninput optical fiber 11; output optical fibers 12 ₁, 12 ₂; mirrors 13 ₁,13 ₂; and mirror driving parts 14 ₁, 14 ₂. Two wavelengths λ₁, λ₂ oflight emitted from the end face of the input optical fiber 11 are madeincident on the end face of any of the output optical fibers 12 ₁, 12 ₂.The optical device control apparatus 2B includes light-branching parts15 ₁, 15 ₂; photodiodes 16 ₁, 16 ₂; detection circuits 17 ₁, 17 ₂; anoptical multi/demultiplexing part 18; and a control part 19; andcontrols the optical device 2A. The optical module 2 in accordance withthe second embodiment differs from the optical module 1 in accordancewith the first embodiment in that it comprises a single input opticalfiber 11 and further comprises the optical multi/demultiplexing part 18.

The optical multi/demultiplexing part 18 inputs and demultiplexesmultiplexed light having two wavelengths λ₁, λ₂ emitted from the endface of the input optical fiber 11, and outputs one light component λ₁to the mirror 13 ₁, and the other light component λ₂ to the mirror 13 ₂.The mirror 13 ₁ reflects the light λ₁ outputted from the opticalmulti/demultiplexing part 18, such that thus reflected light λ₁ isincident on the end face of any of the output optical fibers 12 ₁, 12 ₂.On the other hand, the mirror 13 ₂ reflects the light λ₂ outputted fromthe optical multi/demultiplexing part 18, such that thus reflected lightλ₂ is incident on the end face of any of the output optical fibers 12 ₁,12 ₂. The other constituents are the same as those in the firstembodiment.

The control part 19 causes the mirror driving parts 14 ₁, 14 ₂ tocontrol the respective inclinations of the reflecting surfaces of themirrors 13 ₁, 13 ₂, thereby making the optical module 2 act as anoptical switch. Namely, the control part 19 can cause the light λ₁outputted from the end face of the input optical fiber 11 to be madeincident on the end face of the output optical fiber 12 ₁, and the lightλ₂ outputted from the end face of the input optical fiber 11 to be madeincident on the end face of the output optical fiber 12 ₂. The controlpart 19 can cause the light λ₁ outputted from the end face of the inputoptical fiber 11 to be made incident on the end face of the outputoptical fiber 12 ₂, and the light λ₂ outputted from the end face of theinput optical fiber 11 to be made incident on the end face of the outputoptical fiber 12 ₁. The control part 19 can cause both of the twowavelengths λ₁, λ₂ of light outputted from the end face of the inputoptical fiber 11 to be made incident on the end face of the outputoptical fiber 12 ₁. The control part 19 can cause both of the twowavelengths λ₁, λ₂ of light outputted from the end face of the inputoptical fiber 11 to be made incident on the end face of the outputoptical fiber 12 ₂.

In FIG. 2, the light λ₁ demultiplexed by the opticalmulti/demultiplexing part 18 after being outputted from the end face ofthe input optical fiber 11 is reflected by the mirror 13 ₁, so as to bemade incident on the end face of the output optical fiber 12 ₁, and thelight λ₂ demultiplexed by the optical multi/demultiplexing part 18 afterbeing outputted from the end face of the input optical fiber 11 isreflected by the mirror 13 ₂, so as to be made incident on the end faceof the output optical fiber 12 ₂.

The control part 19 orders the mirror driving part 14 ₁ to vibrate thenormal direction of the reflecting surface of the mirror 13 ₁ at afrequency f₁ about a predetermined direction, detects a component of thefrequency f₁ in the electric signal outputted from the detection circuit17 ₁, and determines whether or not there is optical coupling of thelight λ₁ from the input optical fiber 11 to the output optical fiber 12₁ or the extent thereof according to the result of detection. Further,according to the result of detection, the control part 19 orders themirror driving part 14 ₁ to adjust the normal direction of thereflecting surface of the mirror 13 ₁, thereby controlling the extent ofoptical coupling of the light λ₁ from the input optical fiber 11 to theoutput optical fiber 12 ₁.

The control part 19 orders the mirror driving part 14 ₂ to vibrate thenormal direction of the reflecting surface of the mirror 13 ₂ at afrequency f₂ about a predetermined direction, detects a component of thefrequency f₂ in the electric signal outputted from the detection circuit17 ₂, and determines whether or not there is optical coupling of thelight λ₂ from the input optical fiber 11 to the output optical fiber 12₂ or the extent thereof according to the result of detection. Further,according to the result of detection, the control part 19 orders themirror driving part 14 ₂ to adjust the normal direction of thereflecting surface of the mirror 13 ₂, thereby controlling the extent ofoptical coupling of the light λ₂ from the input optical fiber 11 to theoutput optical fiber 12 ₂.

An example of operation of the optical module 2 in accordance with thesecond embodiment will now be explained together with the optical devicecontrol method in accordance with the second embodiment. Under thecontrol of the control part 19, the optical module 2 operates asfollows, for example. The light components λ₁, λ₂ outputted from the endface of the input optical fiber 11 are demultiplexed by the opticalmulti/demultiplexing part 18, such that one light component λ₁ is madeincident on the reflecting surface of the mirror 13 ₁, whereas the otherlight component λ₂ is made incident on the reflecting surface of themirror 13 ₂.

In response to an order to switch between optical paths from the controlpart 19, the mirror driving part 14 ₁ adjusts the inclination of thereflecting surface of the mirror 13 ₃ such that the light λ₁ incident onthe mirror 13 ₃ is reflected thereby so as to be fed to the end face ofthe output optical fiber 12 ₁. Taking the normal direction of thereflecting surface of the mirror 13 ₁ after the adjustment as apredetermined direction, the normal direction of the reflecting surfaceof the mirror 13 ₁ is driven by the mirror driving part 14 ₁, so as tovibrate at the frequency f₁ about the predetermined direction. The lightλ₁ reflected by the reflecting surface of the mirror 13 ₁ is fed to theend face of the output optical fiber 12 ₁ and propagates through theoutput optical fiber 12 ₁. A part of the guided light is caused tobranch out and taken out by the light-branching part 15 ₁, so as to bereceived by the photodiode 16 ₁, whereby the detection circuit 17 ₁outputs an electric signal having a value corresponding to the quantityof light received.

As the reflecting surface of the mirror 13 ₁ vibrates at the frequencyf₁, the intensity of the light λ₁ propagating through the output opticalfiber 12 ₁ is intensity-modified at the frequency f₁ with time, wherebythe electric signal outputted from the detection circuit 17 ₁ is alsointensity-modified at the frequency f₁ with time. The control part 19detects whether or not the electric signal includes a component of thefrequency f₁ or whether the component is strong or weak. According tothe result of detection, whether or not there is optical coupling of thelight λ₁ from the input optical fiber 11 to the output optical fiber 12₁ or the extent thereof is determined. Further, according to the resultof detection, the mirror driving part 14 ₁ adjusts the normal directionof the reflecting surface of the mirror 13 ₁ (the predetermineddirection to become the center of vibration), such that the extent ofoptical coupling of the light λ₁ from the input optical fiber 11 to theoutput optical fiber 12 ₁ is regulated so as to become a predeterminedvalue (e.g., a maximum value, a value not smaller than a certainthreshold, or a certain set value).

Similarly, in response to an order to switch between optical paths fromthe control part 19, the mirror driving part 14 ₂ adjusts theinclination of the reflecting surface of the mirror 13 ₂ such that thelight λ₂ incident on the mirror 13 ₂ is reflected thereby so as to befed to the end face of the output optical fiber 12 ₂. Taking the normaldirection of the reflecting surface of the mirror 13 ₂ after theadjustment as a predetermined direction, the normal direction of thereflecting surface of the mirror 13 ₂ is driven by the mirror drivingpart 14 ₂, so as to vibrate at the frequency f₂ about the predetermineddirection. The light λ₂ reflected by the reflecting surface of themirror 13 ₂ is fed to the end face of the output optical fiber 12 ₂ andpropagates through the output optical fiber 12 ₂. A part of the guidedlight is caused to branch out and taken out by the light-branching part15 ₂, so as to be received by the photodiode 16 ₂, whereby the detectioncircuit 17 ₂ outputs an electric signal having a value corresponding tothe quantity of light received.

As the reflecting surface of the mirror 13 ₂ vibrates at the frequencyf₂, the intensity of the light X₂ propagating through the output opticalfiber 12 ₂ is intensity-modified at the frequency f₂ with time, wherebythe electric signal outputted from the detection circuit 17 ₂ is alsointensity-modified at the frequency f₂ with time. The control part 19detects whether or not the electric signal includes a component of thefrequency f₂ or whether the component is strong or weak. According tothe result of detection, whether or not there is optical coupling of thelight λ₂ from the input optical fiber 11 to the output optical fiber 12₂ or the extent thereof is determined. Further, according to the resultof detection, the mirror driving part 14 ₂ adjusts the normal directionof the reflecting surface of the mirror 13 ₂ (the predetermineddirection to become the center of vibration), such that the extent ofoptical coupling of the light A₂ from the input optical fiber 11 to theoutput optical fiber 12 ₂ is regulated so as to become a predeterminedvalue.

As such, the optical module 2 in accordance with this embodimentdirectly determines whether or not there is optical coupling from theinput optical fiber to the output optical fiber or the extent thereof,and thus can detect and control the extent of optical coupling with ahigh accuracy. Vibrating the normal direction of the reflecting surfaceof one mirror 13 ₁ at the frequency f₁ and the normal direction of thereflecting surface of the other mirror 13 ₂ at the frequency f₂ (≠f₁)can determine which of the mirrors 13 ₁, 13 ₂ reflects the light coupledto the output optical fiber 12 ₁, 12 ₂. Vibrating the normal directionof the reflecting surface of the mirror reflecting one light componentλ₁ emitted from the end face of one input optical fiber 11 at thefrequency f, and the normal direction of the reflecting surface of themirror reflecting the other light component λ₂ emitted from the end faceof the input optical fiber 11 at the frequency f₂ (≠f₁) can determinewhich wavelength of light is coupled to the optical fiber 12 ₁, 12 ₂.

[Third Embodiment]

A third embodiment of the optical device control apparatus and methodand optical module in accordance with the present invention will now beexplained. FIG. 3 is a diagram which shows a configuration of theoptical module 3 in accordance with the third embodiment. The opticalmodule 3 shown in this drawing comprises an optical device 3A and anoptical device control apparatus 3B. The optical device 3A includesinput optical fibers 11 ₁, 11 ₂; output optical fibers 12 ₁, 12 ₂;mirrors 13 ₁, 13 ₂; and mirror driving parts 14 ₁, 14 ₂. Two wavelengthsλ₁, λ₂ of light emitted from the end faces of the input optical fibers11 ₁, 11 ₂ are made incident on the end face of any of the outputoptical fibers 12 ₁, 12 ₂. The optical device control apparatus 3Bincludes light-branching parts 15 ₁, 15 ₂; photodiodes 16 ₁, 16 ₂;detection circuits 17 ₁, 17 ₂; an optical multi/demultiplexing part 18;and a control part 19; and controls the optical device 3A. The opticalmodule 3 in accordance with the third embodiment differs from theoptical module 2 in accordance with the second embodiment in that itcomprises two input optical fibers 11 ₁, 11 ₂ and in that each of thereflecting surfaces of the mirrors 13 ₁, 13 ₂ is inclinable with respectto two axes.

The optical multi/demultiplexing part 18 inputs and demultiplexesmultiplexed light having two wavelengths λ₁, λ₂ emitted from the endfaces of the input optical fibers 11 ₁, 11 ₂, and outputs thedemultiplexed light components to the mirrors 13 ₁, 13 ₂. The mirror 13₁ reflects the light outputted from the optical multi/demultiplexingpart 18, such that thus reflected light is incident on the end face ofany of the output optical fibers 12 ₁, 12 ₂. On the other hand, themirror 13 ₂ reflects the light outputted from the opticalmulti/demultiplexing part 18, such that thus reflected light is incidenton the end face of any of the output optical fibers 12 ₁, 12 ₂.

Each of the reflecting surfaces of the mirrors 13 ₁, 13 ₂ is inclinablewith respect to two axes. The control part 19 vibrates the normaldirection of the reflecting surface of the mirror reflecting the lightemitted from the end face of one input optical fiber 11 ₁ at a frequencyf_(f1) on a first surface, and the normal direction of the reflectingsurface of the mirror reflecting the light emitted from the end face ofthe other input optical fiber 11 ₂ at a frequency f_(f2) (≠f_(f1)) onthe first surface. The control part 19 vibrates the normal direction ofthe reflecting surface of the mirror reflecting the light λ₁ at afrequency f_(w1) on a second surface, and the normal direction of thereflecting surface of the mirror reflecting the light λ₂ at a frequencyf_(w2) (≠f_(w1)) on the second surface. The first surface is a virtualplane in which the normal direction of the reflecting surface existswhen the mirror vibrates with respect to the first axis, whereas thesecond surface is a virtual plane in which the normal direction of thereflecting surface exists when the mirror vibrates with respect to thesecond axis. The first and second surfaces differ from each other. Forexample, when the mirror 13 ₁ reflects the light λ₁ outputted from theinput optical fiber 11 ₁, the normal direction of the reflecting surfaceof the mirror 13 ₁ vibrates at the frequency f_(f1) on the first surfaceand at the frequency f_(w1) on the second surface.

In FIG. 3, the control part 19 causes the mirror 13 ₁ to reflect thelight λ₁ demultiplexed by the optical multi/demultiplexing part 18 afterbeing outputted from the end face of the input optical fiber 11 ₁, so asto make it incident on the end face of the output optical fiber 12 ₁,and causes the mirror 13 ₂ to reflect the light λ₁ demultiplexed by theoptical multi/demultiplexing part 18 after being outputted from the endface of the input optical fiber 11 ₂, so as to make it incident on theend face of the output optical fiber 12 ₂.

The control part 19 orders the mirror driving part 14 ₁ to vibrate thenormal direction of the reflecting surface of the mirror 13 ₁ about apredetermined direction at the frequency f_(f1) on the first surface andat the frequency f_(w1) on the second surface, detects respectivecomponents of the frequencies f_(f1), f_(w1) in the electric signaloutputted from the detection circuit 17 ₁, and determines whether or notthere is optical coupling of the light λ₁ from the input optical fiber11 ₁ to the output optical fiber 12 ₁ or the extent thereof according tothe result of detection. Further, according to the result of detection,the control part 19 orders the mirror driving part 14 ₁ to adjust thenormal direction of the reflecting surface of the mirror 13 ₁, therebycontrolling the extent of optical coupling of the light λ₁ from theinput optical fiber 11 ₁ to the output optical fiber 12 ₁.

Also, the control part 19 orders the mirror driving part 14 ₂ to vibratethe normal direction of the reflecting surface of the mirror 13 ₂ abouta predetermined direction at the frequency f_(f2) on the first surfaceand at the frequency f_(w1) on the second surface, detects respectivecomponents of the frequencies f_(f2), f_(w1) in the electric signaloutputted from the detection circuit 17 ₂, and determines whether or notthere is optical coupling of the light λ₁ from the input optical fiber11 ₂ to the output optical fiber 12 ₂ or the extent thereof according tothe result of detection. Further, according to the result of detection,the control part 19 orders the mirror driving part 14 ₂ to adjust thenormal direction of the reflecting surface of the mirror 13 ₂, therebycontrolling the extent of optical coupling of the light λ₁ from theinput optical fiber 11 ₂ to the output optical fiber 12 ₂.

An example of operation of the optical module 3 in accordance with thethird embodiment will now be explained together with the optical devicecontrol method in accordance with the third embodiment. Under thecontrol of the control part 19, the optical module 3 operates asfollows, for example. The light component at the wavelength λ₁ in thelight outputted from the end face of one input optical fiber 11 ₁ ismade incident on the reflecting surface of the mirror 13 ₁ by way of theoptical multi/demultiplexing part 18, whereas the light component at thewavelength λ₁ in the light outputted from the end face of the otherinput optical fiber 11 ₂ is made incident on the reflecting surface ofthe mirror 13 ₂ by way of the optical multi/demultiplexing part 18.

In response to an order to switch between optical paths from the controlpart 19, the mirror driving part 14 ₁ adjusts the inclination of thereflecting surface of the mirror 13 ₁ such that the light λ₁ incident onthe mirror 13 ₁ is reflected thereby so as to be fed to the end face ofthe output optical fiber 12 ₁. Taking the normal direction of thereflecting surface of the mirror 13 ₁ after the adjustment as apredetermined direction, the normal direction of the reflecting surfaceof the mirror 13 ₁ is driven by the mirror driving part 14 ₁, so as tovibrate about the predetermined direction at the frequency f_(f1) on thefirst surface and at the frequency f_(w1) on the second surface. Thelight λ₁ reflected by the reflecting surface of the mirror 13 ₁ is fedto the end face of the output optical fiber 12 ₁ and propagates throughthe output optical fiber 12 ₁. A part of the guided light is caused tobranch out and taken out by the light-branching part 15 ₁, so as to bereceived by the photodiode 16 ₁, whereby the detection circuit 17 ₁outputs an electric signal having a value corresponding to the quantityof light received.

The intensity of the light λ₁ propagated through the output opticalfiber 12 ₁ as the reflecting surface of the mirror 13 ₁ vibrates at thefrequencies f_(f1), f_(w1) includes the respective intensity modulationcomponents at the frequencies f_(f1), f_(w1). The electric signaloutputted from the detection circuit 17 ₁ also includes the respectiveintensity modulation components at the frequencies f_(f1), f_(w1). Thecontrol part 19 detects whether or not the components of frequenciesf_(f1), f_(w1) are included in the electric signal or whether they arestrong or weak, and determines whether or not there is optical couplingof the light λ₁ from the input optical fiber 11 ₁ to the output opticalfiber 12 ₁ or the extent thereof according to the result of detection.Further, according to the result of detection, the mirror driving part14 ₁ adjusts the normal direction of the reflecting surface of themirror 13 ₁ (the predetermined direction to become the center ofvibration), such that the extent of optical coupling of the light λ₁from the input optical fiber 11 ₁ to the output optical fiber 12 ₁ isregulated so as to become a predetermined value (e.g., a maximum value,a value not smaller than a certain threshold, or a certain set value).

Similarly, in response to an order to switch between optical paths fromthe control part 19, the mirror driving part 14 ₂ adjusts theinclination of the reflecting surface of the mirror 13 ₂ such that thelight λ₁ incident on the mirror 13 ₂ is reflected thereby so as to befed to the end face of the output optical fiber 12 ₂. Taking the normaldirection of the reflecting surface of the mirror 13 ₂ after theadjustment as a predetermined direction, the normal direction of thereflecting surface of the mirror 13 ₂ is driven by the mirror drivingpart 14 ₂, so as to vibrate about the predetermined direction at thefrequency f_(f2) on the first surface and at the frequency f_(w1) on thesecond surface. The light λ₁ reflected by the reflecting surface of themirror 13 ₂ is fed to the end face of the output optical fiber 12 ₂ andpropagates through the output optical fiber 12 ₂. A part of the guidedlight is caused to branch out and taken out by the light-branching part15 ₂, so as to be received by the photodiode 16 ₂, whereby the detectioncircuit 17 ₂ outputs an electric signal having a value corresponding tothe quantity of light received.

The intensity of the light λ₁ propagated through the output opticalfiber 12 ₂ as the reflecting surface of the mirror 13 ₂ vibrates at thefrequencies f_(f2), f_(w1) includes the respective intensity modulationcomponents at the frequencies f_(f2), f_(w1). The electric signaloutputted from the detection circuit 17 ₂ also includes the respectiveintensity modulation components at the frequencies f_(f2), f_(w1). Thecontrol part 19 detects whether or not the components of frequenciesf_(f2), f_(w1) are included in the electric signal or whether they arestrong or weak, and determines whether or not there is optical couplingof the light λ₁ from the input optical fiber 11 ₂ to the output opticalfiber 12 ₂ or the extent thereof according to the result of detection.Further, according to the result of detection, the mirror driving part14 ₂ adjusts the normal direction of the reflecting surface of themirror 13 ₂ (the predetermined direction to become the center ofvibration), whereby the extent of optical coupling of the light λ₁ fromthe input optical fiber 11 ₂ to the output optical fiber 12 ₂ isregulated so as to become a predetermined value.

As such, the optical module 3 in accordance with this embodimentdirectly determines whether or not there is optical coupling from theinput optical fiber to the output optical fiber, and thus can detect andcontrol the extent of optical coupling with a high accuracy. Also, sinceeach mirror is configured such that an input optical fiber can beidentified by the frequency of vibration of the normal direction of thereflecting surface on the first surface, and the wavelength of light canbe identified by the frequency of vibration of the normal direction ofthe reflecting surface on the second surface, it can be determined atwhich wavelength and from which input optical fiber the light is coupledto an output optical fiber. Also, while the number of mirror vibrationfrequencies required is assumed to be “the number of input opticalfibers×the number of multiplexed wavelengths” as an extension of thesecond embodiment, the number of mirror vibration frequencies requiredin this embodiment is reduced to “the number of input optical fibers+thenumber of multiplexed wavelengths”.

As described above about the predetermined embodiments, the presentinvention can detect and control with a high accuracy whether or notthere is optical coupling or an extent thereof in an optical device.

1. An optical device control apparatus for controlling an optical deviceincluding a mirror in which light emitted from an input opticalwaveguide is reflected by an inclinable reflecting surface so as to bemade incident on an output optical waveguide, and a mirror driving partfor adjusting an inclination of the reflecting surface of the mirror;the apparatus comprising: a light-branching part for taking out a partof the light propagating through the output optical waveguide afterbeing made incident thereon; a light-detecting part for detecting anintensity of the light taken out by the light-branching part andoutputting an electric signal having a value corresponding to thusdetected intensity of light; and a control part for ordering the mirrordriving part to vibrate a normal direction of the reflecting surface ofthe mirror at a predetermined frequency about a predetermined direction,detecting a component of the predetermined frequency in the electricsignal outputted from the light-detecting part, and determining whetheror not there is optical coupling from the input optical waveguide to theoutput optical waveguide or an extent thereof according to a result ofthe detection.
 2. The optical device control apparatus according toclaim 1, wherein the control part controls the extent of opticalcoupling from the input optical waveguide to the output opticalwaveguide by ordering the mirror driving part to adjust the normaldirection of the reflecting surface of the mirror according to theresult of detection.
 3. The optical device control apparatus accordingto claim 1, wherein the optical device comprises a plurality of mirrors;and wherein the control part orders the mirror driving part to vibraterespective normal directions of reflecting surfaces of the mirrors atfrequencies different from each other.
 4. The optical device controlapparatus according to claim 1, wherein the optical device comprises aplurality of input optical waveguides; and wherein the control partorders the mirror driving part to vibrate the normal direction of thereflecting surface of the mirror at respective frequencies differentfrom each other for the input optical waveguides.
 5. The optical devicecontrol apparatus according to claim 1, wherein the optical devicefurther comprises an optical multi/demultiplexing part for multiplexingor demultiplexing light onto an optical path from the input opticalwaveguide to the output optical waveguide; and wherein the control partorders the mirror driving part to vibrate the normal direction of thereflecting surface of the mirror at respective frequencies differentfrom each other for wavelengths of light multiplexed or demultiplexed bythe optical multi/demultiplexing part.
 6. The optical device controlapparatus according to claim 1, wherein the optical device comprises aplurality of input optical waveguides, and further comprises an opticalmulti/demultiplexing part for multiplexing or demultiplexing light ontoan optical path from the input optical waveguide to the output opticalwaveguide, the reflecting surface of the mirror being inclinable abouteach of two axes; wherein the control part orders the mirror drivingpart to vibrate the normal direction of the reflecting surface of themirror on a first surface at respective frequencies different from eachother for the plurality of input optical waveguides, and vibrate thenormal direction of the reflecting surface of the mirror on a secondsurface at respective frequencies different from each other forwavelengths of light multiplexed or demultiplexed by the opticalmulti/demultiplexing part.
 7. The optical device control apparatusaccording to claim 1, wherein the control part regularly orders themirror driving part to vibrate the reflecting surface of the mirror anddetects the component of the predetermined frequency in the electricsignal outputted from the light-detecting part.
 8. The optical devicecontrol apparatus according to claim 1, wherein the control part orders,in response to a request from outside, the mirror driving part tovibrate the reflecting surface of the mirror and detects the componentof the predetermined frequency in the electric signal outputted from thelight-detecting part.
 9. The optical device control apparatus accordingto claim 1, wherein the optical device comprises a plurality of mirrors;and wherein the control part orders the mirror driving part to vibratethe reflecting surface of the mirror and detects the component of thepredetermined frequency in the electric signal outputted from thelight-detecting part sequentially for the plurality of mirrors.
 10. Theoptical device control apparatus according to claim 1, wherein theoptical device comprises a plurality of mirrors; and wherein the controlpart orders the mirror driving part to vibrate the reflecting surface ofthe mirror and detects the component of the predetermined frequency inthe electric signal outputted from the light-detecting partsimultaneously for the plurality of mirrors.
 11. An optical modulecomprising: an optical device including a mirror in which light emittedfrom an input optical waveguide is reflected by an inclinable reflectingsurface so as to be made incident on an output optical waveguide, and amirror driving part for adjusting an inclination of the reflectingsurface of the mirror; and the optical device control apparatusaccording to claim 1 for controlling the optical device.
 12. An opticaldevice control method for controlling an optical device including amirror in which light emitted from an input optical waveguide isreflected by an inclinable reflecting surface so as to be made incidenton an output optical waveguide, and a mirror driving part for adjustingan inclination of the reflecting surface of the mirror; the methodcomprising the steps of: taking out a part of the light propagatingthrough the output optical waveguide after being made incident thereon;obtaining an electric signal having a value corresponding to anintensity of the part of the light; and ordering the mirror driving partto vibrate a normal direction of the reflecting surface of the mirror ata predetermined frequency about a predetermined direction, detecting acomponent of the predetermined frequency in the electric signal, anddetermining whether or not there is optical coupling from the inputoptical waveguide to the output optical waveguide or an extent thereofaccording to a result of the detection.
 13. The optical device controlmethod according to claim 12, wherein the method controls the extent ofoptical coupling from the input optical waveguide to the output opticalwaveguide by ordering the mirror driving part to adjust the normaldirection of the reflecting surface of the mirror according to theresult of detection.
 14. The optical device control method according toclaim 12, wherein the optical device comprises a plurality of mirrors;and wherein the method orders the mirror driving part to vibraterespective normal directions of reflecting surfaces of the mirrors atfrequencies different from each other.
 15. The optical device controlmethod according to claim 12, wherein the optical device comprises aplurality of input optical waveguides; and wherein the method orders themirror driving part to vibrate the normal direction of the reflectingsurface of the mirror at respective frequencies different from eachother for the input optical waveguides.
 16. The optical device controlmethod according to claim 12, wherein the optical device furthercomprises an optical multi/demultiplexing part for multiplexing ordemultiplexing light onto an optical path from the input opticalwaveguide to the output optical waveguide; and wherein the method ordersthe mirror driving part to vibrate the normal direction of thereflecting surface of the mirror at respective frequencies differentfrom each other for wavelengths of light multiplexed or demultiplexed bythe optical multi/demultiplexing part.
 17. The optical device controlmethod according to claim 12, wherein the optical device comprises aplurality of input optical waveguides, and further comprises an opticalmulti/demultiplexing part for multiplexing or demultiplexing light ontoan optical path from the input optical waveguide to the output opticalwaveguide, the reflecting surface of the mirror being inclinable abouteach of two axes; wherein the method orders the mirror driving part tovibrate the normal direction of the reflecting surface of the mirror ona first surface at respective frequencies different from each other forthe plurality of input optical waveguides, and vibrate the normaldirection of the reflecting surface of the mirror on a second surface atrespective frequencies different from each other for wavelengths oflight multiplexed or demultiplexed by the optical multi/demultiplexingpart.
 18. The optical device control method according to claim 12,wherein the method regularly orders the mirror driving part to vibratethe reflecting surface of the mirror and detects the component of thepredetermined frequency in the electric signal.
 19. The optical devicecontrol method according to claim 12, wherein the method orders, inresponse to a request from outside, the mirror driving part to vibratethe reflecting surface of the mirror and detects the component of thepredetermined frequency in the electric signal.
 20. The optical devicecontrol method according to claim 12, wherein the optical devicecomprises a plurality of mirrors; and wherein the method orders themirror driving part to vibrate the reflecting surface of the mirror anddetects the component of the predetermined frequency in the electricsignal sequentially for the plurality of mirrors.
 21. The optical devicecontrol method according to claim 12, wherein the optical devicecomprises a plurality of mirrors; and wherein the method orders themirror driving part to vibrate the reflecting surface of the mirror anddetects the component of the predetermined frequency in the electricsignal simultaneously for the plurality of mirrors.